#define _CRT_SECURE_NO_WARNINGS   1

#include<iostream>
using namespace std;
int dp[50]{0};

class Solution {
public:
	int jumpFloor(int number) {
		dp[0] = 1, dp[1] = 1;
		for (int i = 2; i <= number; i++) 
			dp[i] = dp[i - 1] + dp[i - 2];
		return dp[number];
	}
};

int main()
{
	int n;
	cin >> n;
	Solution sol;
	cout << sol.jumpFloor(n);
	return 0;
}